Retro Style VFO Has Single-Digit Parts Count

December 2, 2025 by 2 Comments

Not every project has to be complicated– reinventing the wheel has its place, but sometimes you find a module or two that does exactly what you want, and the project is more than halfway done. That the kind of project [mircemk]’s Simple Retro Style VFO is — it’s a variable frequency oscillator for HAM and other use, built with just a couple of modules.

Strictly speaking, this is all you need for the project.

The modules in question are the SI5351 Clock Generator module, which is a handy bit of kit with its own crystal reference and PLL to generate frequencies up to 150 MHz, and the Elecrow CrowPanel 1.28inch-HMI ESP32 Rotary Display. The ESP32 in the CrowPanel controls the SI5351 module via I2C; control is via the rest of the CrowPanel module. This Rotary Display is a circular touchscreen surrounded by a rotary display, so [mircmk] has all the inputs he needs to control the VFO.

To round out the parts count, he adds an appropriate connector, plus a power switch, red LED and a lithium battery. One could include a battery charger module as well, but [mircmk] didn’t have one on hand. Even if he had, that still keeps the parts count well inside the single digits. If you like video, we’ve embedded his about the project below; if not the write up on Hackaday.io is upto [mircmk]’s typical standard. 

People have been using the SI5351 to make VFOs for years now, but the addition of the round display makes for a delightfully retro presentation.

Thanks to [mircmk] for the tip.

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LoRa Repeater Lasts 5 Years On PVC Pipe And D Cells

December 2, 2025 by 25 Comments

Sometimes it makes sense to go with plain old batteries and off-the-shelf PVC pipe. That’s the thinking behind [Bertrand Selva]’s clever LoRaTube project.

PVC pipe houses a self-contained LoRa repeater, complete with a big stack of D-size alkaline cells.

LoRa is a fantastic solution for long-range and low-power wireless communication (and popular, judging by the number of projects built around it) and LoRaTube provides an autonomous repeater, contained entirely in a length of PVC pipe. Out the top comes the antenna and inside is all the necessary hardware, along with a stack of good old D-sized alkaline cells feeding a supercap-buffered power supply of his own design. It’s weatherproof, inexpensive, self-contained, and thanks to extremely low standby current should last a good five years by [Bertrand]’s reckoning.

One can make a quick LoRa repeater in about an hour but while the core hardware can be inexpensive, supporting electronics and components (not to mention enclosure) for off-grid deployment can quickly add significant cost. Solar panels, charge controllers, and a rechargeable power supply also add potential points of failure. Sometimes it makes more sense to go cheap, simple, and rugged. Eighteen D-sized alkaline cells stacked in a PVC tube is as rugged as it is affordable, especially if one gets several years’ worth of operation out of it.

You can watch [Bertrand] raise a LoRaTube repeater and do a range test in the video (French), embedded below. Source code and CAD files are on the project page. Black outdoor helper cat not included.

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Retrotechtacular: Learning The Slide Rule The New Old Fashioned Way

December 2, 2025 by 4 Comments

Learning something on YouTube seems kind of modern. But if you are watching a 1957 instructional film about slide rules, it also seems old-fashioned. But Encyclopædia Britannica has a complete 30-minute training film, which, what it lacks in glitz, it makes up for in mathematical rigor.

We appreciated that it started out talking about numbers and significant figures instead of jumping right into the slide rule. One thing about the slide rule is that you have to sort of understand roughly what the answer is. So, on a rule, 2×3, 20×30, 20×3, and 0.2×300 are all the same operation.

You don’t actually get to the slide rule part for about seven minutes, but it is a good idea to watch the introductory part. The lecturer, [Dr. Havery E. White] shows a fifty-cent plastic rule and some larger ones, including a classroom demonstration model. We were a bit surprised that the prestigious Britannica wouldn’t have a bit better production values, but it is clear. Perhaps we are just spoiled by modern productions.

We love our slide rules. Maybe we are ready for the collapse of civilization and the need for advanced math with no computers. If you prefer reading something more modern, try this post. Our favorites, though, are the cylindrical ones that work the same, but have more digits.

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How Cross-Channel Plumbing Fuelled The Allied March On Berlin

December 2, 2025 by 8 Comments

During World War II, as the Allies planned the invasion of Normandy, there was one major hurdle to overcome—logistics. In particular, planners needed to guarantee a solid supply of fuel to keep the mechanized army functional. Tanks, trucks, jeeps, and aircraft all drink petroleum at a prodigious rate. The challenge, then, was to figure out how to get fuel over to France in as great a quantity as possible.

War planners took a diverse approach. A bulk supply of fuel in jerry cans was produced to supply the initial invasion effort, while plans were made to capture port facilities that could handle deliveries from ocean-going tankers. Both had their limitations, so a third method was sought to back them up. Thus was born Operation Pluto—an innovative plan to simply lay fuel pipelines right across the English channel.

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A Stylish Moon And Tide Clock For The Mantlepiece

December 2, 2025 by 3 Comments

Assuming you’re not stuck in a prison cell without windows, you could feasibly keep track of the moon and tides by walking outside and jotting things down in your notebook. Alternatively, you could save a lot of hassle by just building this moon and tide clock from [pjdines1994] instead.

The build is based on a Raspberry Pi Pico W, which is hooked up to a real-time clock module and a Waveshare 3.7-inch e-paper display. Upon this display, the clock draws an image relevant to the current phase of the moon. As the write-up notes, it was a tad fussy to store 24 images for all the different lunar phases within the Pi Pico, but it was achieved nonetheless with a touch of compression. As for tides, it covers those too by pulling in tide information from an online resource.

It’s specifically set up to report the local tides for [pjdines1994], reporting the high tide and low tide times for Whitstable in the United Kingdom. If you’re not in Whitstable, you’d probably want to reconfigure the clock before using it yourself. Unless you really want to know what’s up in Whitstable, of course. If you so wish, you can set the clock up to make its own tide predictions by running local calculations, but [pjdines1994] notes that this is rather more complicated to do. The finished result look quite good, because [pjdines1994] decided to build it inside an old carriage clock that only reveals parts of the display showing the moon and the relevant tide numbers.

We’ve featured some other great tide clocks before, like this grand 3D printed design. If you’ve built your own arcane machine to plot the dances of celestial objects, do be sure to let us know on the tipsline!

Give Us One Manual For Normies, Another For Hackers

December 2, 2025 by 21 Comments

We’ve all been there. You’ve found a beautiful piece of older hardware at the thrift store, and bought it for a song. You rush it home, eager to tinker, but you soon find it’s just not working. You open it up to attempt a repair, but you could really use some information on what you’re looking at and how to enter service mode. Only… a Google search turns up nothing but dodgy websites offering blurry PDFs for entirely the wrong model, and you’re out of luck.

These days, when you buy an appliance, the best documentation you can expect is a Quick Start guide and a warranty card you’ll never use. Manufacturers simply don’t want to give you real information, because they think the average consumer will get scared and confused. I think they can do better. I’m demanding a new two-tier documentation system—the basics for the normies, and real manuals for the tech heads out there.

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Build Your Own Glasshole Detector

December 2, 2025 by 18 Comments

Connected devices are ubiquitous in our era of wireless chips heavily relying on streaming data to someone else’s servers. This sentence might already start to sound dodgy, and it doesn’t get better when you think about today’s smart glasses, like the ones built by Meta (aka Facebook).

[sh4d0wm45k] doesn’t shy away from fighting fire with fire, and shows you how to build a wireless device detecting Meta’s smart glasses – or any other company’s Bluetooth devices, really, as long as you can match them by the beginning of the Bluetooth MAC address.

[sh4d0wm45k]’s device is a mini light-up sign saying “GLASSHOLE”, that turns bright white as soon as a pair of Meta glasses is detected in the vicinity. Under the hood, a commonly found ESP32 devboard suffices for the task, coupled to two lines of white LEDs on a custom PCB. The code is super simple, sifting through packets flying through the air, and lets you easily contribute with your own OUIs (Organizationally Unique Identifier, first three bytes of a MAC address). It wouldn’t be hard to add such a feature to any device of your own with Arduino code under its hood, or to rewrite it to fit a platform of your choice.

We’ve been talking about smart glasses ever since Google Glass, but recently, with Meta’s offerings, the smart glasses debate has reignited. Due to inherent anti-social aspects of the technology, we can see what’d motivate one to build such a hack. Perhaps, the next thing we’ll see is some sort of spoofed packets shutting off the glasses, making them temporarily inoperable in your presence in a similar way we’ve seen with spamming proximity pairing packets onto iPhones.